Hand-held ejector-type dispensing systems have long been used for delivery of multiple-part silicone dental impression materials. The standard in the industry has heretofore been use of polypropylene as the material of choice for manufacture of the cartridge body.
Multiple-part hydrophilic silicones for use in dental impression taking are disclosed, for example, in U.S. Pat No. 4,657,959 to Bryan et. al. Devices useful for delivery of such materials include multiple barrel dispensing devices having a static mixer provided to efficiently mix the separate components as they are extruded from the barrels of the device. An example of such a device is described in U.S. Pat. No. 4,538,920 to Drake.
U.S. Pat. No. 5,100,320 discloses a cartridge for delivery of dental compositions. The material from which the cartridge is manufactured must have a burst strength greater than that of an otherwise identical cartridge made entirely of polypropylene and a 24 hour water absorption less than nylon-6. These materials are discussed at column 4, lines 3-12.